For many decades following the introduction of the automobile, the conventional fuel cap was of the threaded or bayonet lock type which, eventually, was covered by a pivotable fuel inlet cover integrally formed with the design of the vehicle body. More recently, and in order to improve the user experience, the fuel cap has been replaced in many applications with a capless fuel inlet having a spring-loaded flapper arrangement to close the inlet once fueling has been completed. Like the traditional fuel cap, the capless fuel inlet is covered by a pivotable fuel inlet cover that is also integrally formed with the design of the vehicle body.
The spring-loaded flapper arrangement of a typical capless fuel inlet includes two pivotable covers or flappers. One of these covers is the outer cover that is seen by the user during refueling once the pivotable fuel inlet cover is opened. The other cover is the inner cover pushed upon by the tip of the fuel nozzle after insertion of the nozzle into the fuel inlet. Each cover or flapper has its own defined functionality and role in the capless fuel inlet. However, movement of each of the covers is regulated by a mechanical spring.
While producing generally satisfactory results, the typical capless fuel inlet may be improved. A limitation of known capless fuel inlet arrangements is related to the countered design requirements. It is understood that the springs must demonstrate sufficient stiffness so as to secure the covers tightly enough between fueling so as to prevent evaporative emissions (EVAP) leaks. However, it is also understood that the springs must demonstrate sufficient softness so as prevent the user from having to apply an unreasonable amount of force when inserting the nozzle for fueling. The relative ease of insertion is particularly an issue when the operator is physically compromised.
In addition, the matter of the level of ease related to nozzle insertion is particularly pronounced in situation of non-integrated refueling canister only system (NIRCOS) sealed fuel tanks. This is because the capless units on the NIRCOS require a stronger spring to withstand the relatively large vacuum excursions experienced during overnight diurnal cooling. Accordingly, the effort needed by the user to insert the nozzle into the capless fuel inlet associated with the NIRCOS fuel tank during refueling is greater than with capless fuel inlets associated with conventional fuel tanks.
As in so many areas of vehicle technology there is always room for improvements related to the design of a capless fuel inlet so as to improve the user experience. Particularly, it would be advantageous to provide a capless fuel inlet in which the biasing forces applied against one or both of the flapper covers may be selectively softened for ease of operator use while being firm enough to provide the force necessary to prevent EVAP leaks. It would be furthermore advantageous to provide such a system that requires little or no maintenance over its anticipated operating life, is highly durable, and that embodies both relatively low production and assembly costs.